RxJavaing

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Observable.just("123").lift(new Observable.Operator<Integer, String>() {            @Override            public Subscriber<? super String> call(final Subscriber<? super Integer> subscriber) {                return new Subscriber<String>() {                    @Override                    public void onCompleted() {                        System.out.println("s====================onCompleted======");                    }                    @Override                    public void onError(Throwable throwable) {                    }                    @Override                    public void onNext(String s) {                        System.out.println("s=========================="+s);                        subscriber.onNext(Integer.parseInt(s));                    }                    @Override                    public void onStart() {                        super.onStart();                        System.out.println("s====================onStart======");                    }                };            }        }).subscribe();

怎么调用的啊?


Observable.just("123")? 它干了什么.分析源码

Observable observable = Observable.create(OnSubscribe  小a = new JustOnSubscribe("123");
); // 小A = observable  
------------------------------------------->
Observable.just("123") 等效与 小A
------------------------------------------->
perator 小B = new Observable.Operator<Integer, String>() {
  @Override    
 public Subscriber<? super String> call(final Subscriber<? super Integer> subscriber) 
  {          
    return 小C;    
  }
}
Subscriber 小C = new Subscriber<String>() {
        @Override 
public void onCompleted() {  
   System.out.println("s====================onCompleted======");            
}           
 @Override
public void onError(Throwable throwable) { 
  }            
@Override            
public void onNext(String s) {                
System.out.println("s=========================="+s);                
subscriber.onNext(Integer.parseInt(s));  // subscriber 在小B call中传入 
Subscriber action= new ActionSubscriber(onNext,onError,onCompleted);
// subscriber 就是它---------------------------------------------->>>          
}            

@Override           
public void onStart() {                
super.onStart();                
System.out.println("s====================onStart======");            
}        
}
==========================================================================
Observable.just("123").lift(小B).subscribe();
---------->小A.lift(小B).subscribe();
------------->小A.lift(小B) = 大A
Observable 大A = Observable.create(OnSubscribe  大a = new OnSubscribeLift(小a,小B);
); 
------------------------->大A.subscribe();
static <T> Subscription subscribe(Subscriber<? super T> subscriber, Observable<T> observable) {            ((Subscriber)subscriber).onStart(); // 1    RxJavaHooks.onObservableStart(observable, observable.onSubscribe).call(subscriber); //2            return RxJavaHooks.onObservableReturn((Subscription)subscriber); // 3        }    }}

Subscriber action= new ActionSubscriber(onNext,onError,onCompleted);
// 1 --> action.start // 不关注,subscribe方法会构造一个 内容观察者,暂时没用到它,不关注
RxJavaHooks.onObservableStart(observable, observable.onSubscribe).call(subscriber);
RxJavaHooks.onObservableStart(observable, observable.onSubscribe) = RxJavaHooks.onObservableStart(大A, 大a).call(action);
RxJavaHooks.onObservableStart(大A, 大a) = 大a
RxJavaHooks.onObservableStart(observable, observable.onSubscribe).call(subscriber);
翻译后是
--------->大a.call(action); // action 此时不用关注,
-----------> 大a = new OnSubscribeLift(小a,小B);
    OnSubscribeLift call 方法如下this.operator = 小B
this.parent = 小a
public void call(Subscriber<? super R> o) {        Subscriber e = (Subscriber)RxJavaHooks.onObservableLift(this.operator).call(o);        e.onStart();        this.parent.call(e);}
------------------------>小C = 小B.call(action)
--------------------------->小C.onStart()----------------------------------------->OnStart调用
------------------------------>小a.call(小C);
OnSubscribe  小a = new JustOnSubscribe("123");
public void call(Subscriber<? super T> s) {    s.setProducer(ScalarSynchronousObservable.createProducer(s, this.value));
    等效与
    小C.setProducer(WeakSingleProducer(小C,"123"));}
public void setProducer(Producer p) {    boolean passToSubscriber = false;    long toRequest;    synchronized(this) {        toRequest = this.requested;        this.producer = p;        if(this.subscriber != null && toRequest == -9223372036854775808L) {            passToSubscriber = true;        }    }    if(passToSubscriber) {        this.subscriber.setProducer(this.producer);    } else if(toRequest == -9223372036854775808L) {        this.producer.request(9223372036854775807L); // 会执行到它9223372036854775807L    } else {        this.producer.request(toRequest);    }}
---------------------------->this.producer = WeakSingleProducer
------------------------------------------------->>request(9223372036854775807L);
static final class WeakSingleProducer<T> implements Producer {    final Subscriber<? super T> actual;    final T value;    boolean once;    public WeakSingleProducer(Subscriber<? super T> actual, T value) {        this.actual = actual;        this.value = value;
等效与
this.actual = 小C;        this.value = "123";
    }    public void request(long n) {        if(!this.once) {            if(n < 0L) {                throw new IllegalStateException("n >= required but it was " + n);            } else if(n != 0L) {                this.once = true;                Subscriber a = this.actual; // a = 小C                if(!a.isUnsubscribed()) {                    Object v = this.value;                    try {                        a.onNext(v); // onNext
----------------------------------------->
onNext调用                    } catch (Throwable var6) {                        Exceptions.throwOrReport(var6, a, v);                        return;                    }                    if(!a.isUnsubscribed()) {                        a.onCompleted(); // onCompleted----------------------------------------->onCompleted
调用

                    }                }            }        }    }}
最终  小C 的onStart onNext onCompleted  得以执行
Subscriber 小C = new Subscriber<String>() {
        @Override 
public void onCompleted() {  
   System.out.println("s====================onCompleted======");            
}           
 @Override
public void onError(Throwable throwable) { 
  }            
@Override            
public void onNext(String s) {                
System.out.println("s=========================="+s);                
subscriber.onNext(Integer.parseInt(s));  // subscriber 在小B call中传入 
Subscriber action= new ActionSubscriber(onNext,onError,onCompleted);
// subscriber 就是它---------------------------------------------->>>          
}            

@Override           
public void onStart() {                
super.onStart();                
System.out.println("s====================onStart======");            
}        
}

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